As ocular axial length measurement apparatuses, an apparatus for measuring an ocular axial length with an optical interferometer and an apparatus for measuring an ocular axial length with an ultrasonic probe are known.
There is a known combo apparatus in which a device for measuring an ocular axial length with an optical interferometer is provided with an ultrasonic probe. Thus, the combo apparatus uses ultrasonic waves to measure an optical interferometer. (see Patent Document 1).